The purpose of the proposed research is to examine the course of development in monkeys for the consequences of surgical lesions of the parietal area of the cerebral neocortex made in infancy or midmaturity. Electrophysiological recordings from single cells will be made to determine if thresholds, receptive fields, submodal input and somatotopic organization of the cytoarchitectural areas of the parietal cortex are similar to those in the mature animal. Unilateral surgical lesions of the hand representation in areas 3, 1-2, or 5-7 in the postcentral and posterior parietal areas of cortex. The specific behaviors that will be charted are responses to neurological tests, performance on tactile discrimination tasks and use of the hand in exploration and social contact. Electrophysiological and neurohistological methods will be used to determine the extent of the lesions and pattern of recovery that follows early as opposed to late brain damage, to determine if sensory recovery is rapid or extensive enough to permit for normal behavioral development, and to obtain physiological correlates of the basis for the recovery.